The extensive availability of the internet has led to the recognition of problematic internet use, the so-called Internet Addiction (IA), mostly involving adolescents. Burnout can lead to substance abuse or addictive behaviour (such as internet addiction) as a coping method. There are insufficient data about internet addiction and its possible association with burnout in adults, especially among healthcare workers. The aim of our present study was to focus on prevalence and the risk factors of internet addiction and its possible association with burnout among healthcare workers in a single hospital applying a questionnaire-based survey. In total, 49 doctors (10.1%), 198 nurses (40.9%), 123 medical assistant (25.4%), 73 other healthcare workers (15.1%), and 42 (1.7%) healthcare associated workers (cleaning, laundry, etc.) have completed our survey. In a multivariate analysis, IA was associated with age between 18 and 25 (OR: 2.6, p = 0.024), surfing on the internet >5 h daily (OR 25.583, p < 0.001), being single (OR: 4.275, p = 0.006), being childless (OR: 3.81, p = 0.011), working less than five years (OR 2.135, p = 0.048) and job type (being healthcare associated worker, OR: 2.907, p = 0.009). Illicit drug intake (OR 52.494, p < 0.001), and diabetes (OR: 4.122, p = 0.043) were also significantly associated with internet addiction. No association of burnout and IA could be found. A small but significant proportion of our healthcare workers suffered from IA, which was associated with substance abuse and diabetes in multivariate analysis. Our study also draws attention to the risk factors of IA such as younger age, family status, working type and working hours internet use. The possible association of burnout and IA merits further investigation.